In the prior art, such information as the beginning position and ending position of a congested road interval, the total length of the interval, and the time required to traverse the congested interval from the end to the beginning, has been provided as congestion information to the drivers of automobiles by means of radio broadcasts, photoelectric billboards installed along major arteries, and in addition by means of navigation equipment installed in automobiles.
In recent years in particular, systems (for example, the Vehicle Information and Communication System (VICS) for communication of road traffic information) have been introduced in which vehicle detectors and similar which detect traveling vehicles are installed on roadsides, and the information obtained from such vehicle detectors is analyzed at a center to calculate congested intervals and other information. Drivers can reliably obtain detailed congestion information, such as the beginning position and total length of a congested interval, from such a system.
For example, Japanese Patent Laid-open No. 2002-257561 discloses a congestion information provision system and congestion information provision equipment. In this congestion information provision system, such information as the number of vehicles in transit on each road and the vehicle velocity of vehicles in transit is acquired, and based on this traffic information, the beginning position of a congested interval, the congestion length and other information is calculated, and this traffic information is transmitted by wireless means to users. One such congestion information provision system is the Vehicle Information and Communication System (VICS), in which traffic information is transmitted to users from optical beacons, radio beacons, FM multiplex broadcast antennas, and similar.
As traffic information transmitted to users, in addition to construction information indicating the locations of construction sites, accident information indicating the locations of accident sites, road closure information indicating road closures, and similar, there is also common congestion information, necessary to provide individual congestion information (described below) to users. In particular, this common congestion information comprises such information as road numbers which can specify roads in which congestion has occurred for navigation equipment, the beginning and ending positions of congestion, and congestion quantities (for example, congestion lengths).
On the other hand, in order to receive traffic information provided by the congestion information provision system, user vehicles are equipped with navigation equipment comprising the functions of congestion information provision devices. Here, congestion information provision devices are configured so as to receive traffic information provided by a congestion information provision system via a receiving antenna. As this reception portion, for example, an optical beacon receiver or radio beacon receiver which receives traffic information transmitted from the Vehicle Information and Communication System (VICS) to vehicles, as well as an FM receiver which receives traffic information transmitted to vehicles via FM multiplexed broadcasts, may be used.
Thus by means of conventional congestion information provision system and congestion information provision device, through the reception, by a navigation device comprising functions of a congestion information provision device, of traffic information comprising information on a congested interval through which the vehicle itself is passing from the Vehicle Information and Communication System (VICS), congestion information for individual vehicles can be provided to drivers.
Further, Japanese Patent Laid-open No. 2002-73758 discloses an information provision system which performs route searches. In this information provision system, a management server of the information provision system receives a search request for a route, from a departure point to a destination point, from a terminal over the Internet, performs route search processing, and transmits the search result to the terminal. The management server searches public transportation facilities and performs a route search for movement using public transportation facilities, searches road network information and taxi position information and performs a route search for movement using a taxi, searches road network information and performs a route search for movement using an automobile, and searches pedestrian road information and performs a route search for movement on foot, and combines these search results, to perform a route search from the departure point to the destination point.
By this means, a route search can be performed which combines movement using transportation facilities and movement on foot, based on the search conditions, and this search result can be transmitted to a terminal.